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[ARM, AArch64] Make aarch-common.c files more robust.


Hi,

This patch is a respin of the aarch-common improvements to use a generic
search to find SETs and the variety of shifts, rather than relying on the
hope that we will find something well formed.

I've bootstrapped the patch on a chromebook with -mcpu=cortex-a7,
 -mcpu=cortex-a9 and -mcpu=cortex-a15 with no issues, and run
the aarch64-none-elf regression suite with no issues. And I've thrown
a bunch of smoke tests at this over all supported -mcpu values
with no issues, and only a few minor scheduling differences where the
old code was too liberal and did the wrong thing.

Is this OK?

Thanks,
James

---
gcc/

2013-11-06  James Greenhalgh  <james.greenhalgh@arm.com>

	* config/arm/aarch-common.c
	(search_term): New typedef.
	(shift_rtx_costs): New array.
	(arm_rtx_shift_left_p): New.
	(arm_find_sub_rtx_with_search_term): Likewise.
	(arm_find_sub_rtx_with_code): Likewise.
	(arm_early_load_addr_dep): Add sanity checking.
	(arm_no_early_alu_shift_dep): Likewise.
	(arm_no_early_alu_shift_value_dep): Likewise.
	(arm_no_early_mul_dep): Likewise.
	(arm_no_early_store_addr_dep): Likewise.
diff --git a/gcc/config/arm/aarch-common.c b/gcc/config/arm/aarch-common.c
index 3111ae9..201e581 100644
--- a/gcc/config/arm/aarch-common.c
+++ b/gcc/config/arm/aarch-common.c
@@ -31,30 +31,139 @@
 #include "c-family/c-common.h"
 #include "rtl.h"
 
-/* Return nonzero if the CONSUMER instruction (a load) does need
-   PRODUCER's value to calculate the address.  */
+typedef struct
+{
+  rtx_code search_code;
+  rtx search_result;
+  bool find_any_shift;
+} search_term;
+
+/* Return TRUE if X is either an arithmetic shift left, or
+   is a multiplication by a power of two.  */
+static bool
+arm_rtx_shift_left_p (rtx x)
+{
+  enum rtx_code code = GET_CODE (x);
 
-int
-arm_early_load_addr_dep (rtx producer, rtx consumer)
+  if (code == MULT && CONST_INT_P (XEXP (x, 1))
+      && exact_log2 (INTVAL (XEXP (x, 1))) > 0)
+    return true;
+
+  if (code == ASHIFT)
+    return true;
+
+  return false;
+}
+
+static rtx_code shift_rtx_codes[] =
+  { ASHIFT, ROTATE, ASHIFTRT, LSHIFTRT,
+    ROTATERT, ZERO_EXTEND, SIGN_EXTEND };
+
+/* Callback function for arm_find_sub_rtx_with_code.
+   DATA is safe to treat as a SEARCH_TERM, ST.  This will
+   hold a SEARCH_CODE.  PATTERN is checked to see if it is an
+   RTX with that code.  If it is, write SEARCH_RESULT in ST
+   and return 1.  Otherwise, or if we have been passed a NULL_RTX
+   return 0.  If ST.FIND_ANY_SHIFT then we are interested in
+   anything which can reasonably be described as a SHIFT RTX.  */
+static int
+arm_find_sub_rtx_with_search_term (rtx *pattern, void *data)
 {
-  rtx value = PATTERN (producer);
-  rtx addr = PATTERN (consumer);
-
-  if (GET_CODE (value) == COND_EXEC)
-    value = COND_EXEC_CODE (value);
-  if (GET_CODE (value) == PARALLEL)
-    value = XVECEXP (value, 0, 0);
-  value = XEXP (value, 0);
-  if (GET_CODE (addr) == COND_EXEC)
-    addr = COND_EXEC_CODE (addr);
-  if (GET_CODE (addr) == PARALLEL)
+  search_term *st = (search_term *) data;
+  rtx_code pattern_code;
+  int found = 0;
+
+  gcc_assert (pattern);
+  gcc_assert (st);
+
+  /* Poorly formed patterns can really ruin our day.  */
+  if (*pattern == NULL_RTX)
+    return 0;
+
+  pattern_code = GET_CODE (*pattern);
+
+  if (st->find_any_shift)
     {
-      if (GET_CODE (XVECEXP (addr, 0, 0)) == RETURN)
-        addr = XVECEXP (addr, 0, 1);
+      unsigned i = 0;
+
+      /* Left shifts might have been canonicalized to a MULT of some
+	 power of two.  Make sure we catch them.  */
+      if (arm_rtx_shift_left_p (*pattern))
+	found = 1;
       else
-        addr = XVECEXP (addr, 0, 0);
+	for (i = 0; i < ARRAY_SIZE (shift_rtx_codes); i++)
+	  if (pattern_code == shift_rtx_codes[i])
+	    found = 1;
+    }
+
+  if (pattern_code == st->search_code)
+    found = 1;
+
+  if (found)
+    st->search_result = *pattern;
+
+  return found;
+}
+
+/* Traverse PATTERN looking for a sub-rtx with RTX_CODE CODE.  */
+static rtx
+arm_find_sub_rtx_with_code (rtx pattern, rtx_code code, bool find_any_shift)
+{
+  search_term st;
+  int result = 0;
+
+  gcc_assert (pattern != NULL_RTX);
+  st.search_code = code;
+  st.search_result = NULL_RTX;
+  st.find_any_shift = find_any_shift;
+  result = for_each_rtx (&pattern, arm_find_sub_rtx_with_search_term, &st);
+  if (result)
+    return st.search_result;
+  else
+    return NULL_RTX;
+}
+
+/* Traverse PATTERN looking for any sub-rtx which looks like a shift.  */
+static rtx
+arm_find_shift_sub_rtx (rtx pattern)
+{
+  return arm_find_sub_rtx_with_code (pattern, ASHIFT, true);
+}
+
+/* PRODUCER and CONSUMER are two potentially dependant RTX.  PRODUCER
+   (possibly) contains a SET which will provide a result we can access
+   using the SET_DEST macro.  We will place the RTX which would be
+   written by PRODUCER in SET_SOURCE.
+   Similarly, CONSUMER (possibly) contains a SET which has an operand
+   we can access using SET_SRC.  We place this operand in
+   SET_DESTINATION.
+
+   Return nonzero if we found the SET RTX we expected.  */
+static int
+arm_get_set_operands (rtx producer, rtx consumer,
+		      rtx *set_source, rtx *set_destination)
+{
+  rtx set_producer = arm_find_sub_rtx_with_code (producer, SET, false);
+  rtx set_consumer = arm_find_sub_rtx_with_code (consumer, SET, false);
+
+  if (set_producer && set_consumer)
+    {
+      *set_source = SET_DEST (set_producer);
+      *set_destination = SET_SRC (set_consumer);
+      return 1;
     }
-  addr = XEXP (addr, 1);
+  return 0;
+}
+
+/* Return nonzero if the CONSUMER instruction (a load) does need
+   PRODUCER's value to calculate the address.  */
+int
+arm_early_load_addr_dep (rtx producer, rtx consumer)
+{
+  rtx value, addr;
+
+  if (!arm_get_set_operands (producer, consumer, &value, &addr))
+    return 0;
 
   return reg_overlap_mentioned_p (value, addr);
 }
@@ -62,88 +171,56 @@ arm_early_load_addr_dep (rtx producer, rtx consumer)
 /* Return nonzero if the CONSUMER instruction (an ALU op) does not
    have an early register shift value or amount dependency on the
    result of PRODUCER.  */
-
 int
 arm_no_early_alu_shift_dep (rtx producer, rtx consumer)
 {
-  rtx value = PATTERN (producer);
-  rtx op = PATTERN (consumer);
+  rtx value, op;
   rtx early_op;
 
-  if (GET_CODE (value) == COND_EXEC)
-    value = COND_EXEC_CODE (value);
-  if (GET_CODE (value) == PARALLEL)
-    value = XVECEXP (value, 0, 0);
-  value = XEXP (value, 0);
-  if (GET_CODE (op) == COND_EXEC)
-    op = COND_EXEC_CODE (op);
-  if (GET_CODE (op) == PARALLEL)
-    op = XVECEXP (op, 0, 0);
-  op = XEXP (op, 1);
-
-  early_op = XEXP (op, 0);
-  /* This is either an actual independent shift, or a shift applied to
-     the first operand of another operation.  We want the whole shift
-     operation.  */
-  if (REG_P (early_op))
-    early_op = op;
-
-  return !reg_overlap_mentioned_p (value, early_op);
+  if (!arm_get_set_operands (producer, consumer, &value, &op))
+    return 0;
+
+  if ((early_op = arm_find_shift_sub_rtx (op)))
+    {
+      if (REG_P (early_op))
+	early_op = op;
+
+      return !reg_overlap_mentioned_p (value, early_op);
+    }
+
+  return 0;
 }
 
 /* Return nonzero if the CONSUMER instruction (an ALU op) does not
    have an early register shift value dependency on the result of
    PRODUCER.  */
-
 int
 arm_no_early_alu_shift_value_dep (rtx producer, rtx consumer)
 {
-  rtx value = PATTERN (producer);
-  rtx op = PATTERN (consumer);
+  rtx value, op;
   rtx early_op;
 
-  if (GET_CODE (value) == COND_EXEC)
-    value = COND_EXEC_CODE (value);
-  if (GET_CODE (value) == PARALLEL)
-    value = XVECEXP (value, 0, 0);
-  value = XEXP (value, 0);
-  if (GET_CODE (op) == COND_EXEC)
-    op = COND_EXEC_CODE (op);
-  if (GET_CODE (op) == PARALLEL)
-    op = XVECEXP (op, 0, 0);
-  op = XEXP (op, 1);
-
-  early_op = XEXP (op, 0);
-
-  /* This is either an actual independent shift, or a shift applied to
-     the first operand of another operation.  We want the value being
-     shifted, in either case.  */
-  if (!REG_P (early_op))
-    early_op = XEXP (early_op, 0);
-
-  return !reg_overlap_mentioned_p (value, early_op);
+  if (!arm_get_set_operands (producer, consumer, &value, &op))
+    return 0;
+
+  if ((early_op = arm_find_shift_sub_rtx (op)))
+    /* We want to check the value being shifted.  */
+    if (!reg_overlap_mentioned_p (value, XEXP (early_op, 0)))
+      return 1;
+
+  return 0;
 }
 
 /* Return nonzero if the CONSUMER (a mul or mac op) does not
    have an early register mult dependency on the result of
    PRODUCER.  */
-
 int
 arm_no_early_mul_dep (rtx producer, rtx consumer)
 {
-  rtx value = PATTERN (producer);
-  rtx op = PATTERN (consumer);
-
-  if (GET_CODE (value) == COND_EXEC)
-    value = COND_EXEC_CODE (value);
-  if (GET_CODE (value) == PARALLEL)
-    value = XVECEXP (value, 0, 0);
-  value = XEXP (value, 0);
-  if (GET_CODE (op) == COND_EXEC)
-    op = COND_EXEC_CODE (op);
-  if (GET_CODE (op) == PARALLEL)
-    op = XVECEXP (op, 0, 0);
-  op = XEXP (op, 1);
+  rtx value, op;
+
+  if (!arm_get_set_operands (producer, consumer, &value, &op))
+    return 0;
 
   if (GET_CODE (op) == PLUS || GET_CODE (op) == MINUS)
     {
@@ -162,19 +239,17 @@ arm_no_early_mul_dep (rtx producer, rtx consumer)
 int
 arm_no_early_store_addr_dep (rtx producer, rtx consumer)
 {
-  rtx value = PATTERN (producer);
-  rtx addr = PATTERN (consumer);
-
-  if (GET_CODE (value) == COND_EXEC)
-    value = COND_EXEC_CODE (value);
-  if (GET_CODE (value) == PARALLEL)
-    value = XVECEXP (value, 0, 0);
-  value = XEXP (value, 0);
-  if (GET_CODE (addr) == COND_EXEC)
-    addr = COND_EXEC_CODE (addr);
-  if (GET_CODE (addr) == PARALLEL)
-    addr = XVECEXP (addr, 0, 0);
-  addr = XEXP (addr, 0);
+  rtx value = arm_find_sub_rtx_with_code (producer, SET, false);
+  rtx addr = arm_find_sub_rtx_with_code (consumer, SET, false);
+
+  if (value)
+    value = SET_DEST (value);
+
+  if (addr)
+    addr = SET_DEST (addr);
+
+  if (!value || !addr)
+    return 0;
 
   return !reg_overlap_mentioned_p (value, addr);
 }

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